If a runner in a marathon had the 37th fastest time...

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by Brent@GMATPrepNow » Fri Dec 29, 2017 7:17 am
AAPL wrote:If a runner in a marathon had the 37th fastest time and the 50th slowest time, how many runners finished the marathon?

A. 83
B. 84
C. 85
D. 86
E. 87
Runner had the 37th fastest time...
So, there are 36 people IN FRONT of the runner

Runner had the 50th slowest time...
So, there are 49 people BEHIND the runner

How many runners finished the marathon?
We have:
- - - - - 49 people-----the runner--------36 people------
So, the TOTAL number of runners = 49 + 1 + 36 = 86

Answer: D

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by Scott@TargetTestPrep » Mon Sep 02, 2019 6:36 pm
AAPL wrote:If a runner in a marathon had the 37th fastest time and the 50th slowest time, how many runners finished the marathon?

A. 83
B. 84
C. 85
D. 86
E. 87

The OA is D.

I don't have clear this PS question, I appreciate if any expert explain it for me. Thank you so much.
The number of runners in the marathon are 50 + 37 - 1 = 86 runners. We counted the runner in the 50 slowest runners and also in the 37 fastest runners, so the runner has been double-counted. Thus, we subtact that runner one time to compensate for the double counting.

Answer: D

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